U.S. patent application number 14/357815 was filed with the patent office on 2014-10-23 for driving environment prediction device, vehicle control device and methods thereof.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Koji Ito, Michihiro Miyashita, Kouhei Tochigi, Nobukazu Ueki. Invention is credited to Koji Ito, Michihiro Miyashita, Kouhei Tochigi, Nobukazu Ueki.
Application Number | 20140316628 14/357815 |
Document ID | / |
Family ID | 48429092 |
Filed Date | 2014-10-23 |
United States Patent
Application |
20140316628 |
Kind Code |
A1 |
Miyashita; Michihiro ; et
al. |
October 23, 2014 |
DRIVING ENVIRONMENT PREDICTION DEVICE, VEHICLE CONTROL DEVICE AND
METHODS THEREOF
Abstract
There is a need to predict a driving environment with high
responsiveness by a simple configuration. There is provided a
driving environment prediction device that predicts a driving
environment of a vehicle that causes a vehicle stop. The driving
environment prediction device comprises: a first vehicle stop time
rate calculator which is configured to calculate a rate of vehicle
stop time in a first period, as a first vehicle stop time rate
(shorter-period vehicle stop time rate); a second vehicle stop time
rate calculator which is configured to calculate a rate of vehicle
stop time in a second period which is longer than the first period,
as a second vehicle stop time rate (longer-period vehicle stop time
rate); and a driving environment predictor which is configured to
predict the driving environment, based on the shorter-period
vehicle stop time rate and the longer-period vehicle stop time
rate.
Inventors: |
Miyashita; Michihiro;
(Susono-shi, JP) ; Ito; Koji; (Nagoya-shi, JP)
; Ueki; Nobukazu; (Susono-shi, JP) ; Tochigi;
Kouhei; (Susono-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Miyashita; Michihiro
Ito; Koji
Ueki; Nobukazu
Tochigi; Kouhei |
Susono-shi
Nagoya-shi
Susono-shi
Susono-shi |
|
JP
JP
JP
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Toyota-shi
JP
|
Family ID: |
48429092 |
Appl. No.: |
14/357815 |
Filed: |
November 18, 2011 |
PCT Filed: |
November 18, 2011 |
PCT NO: |
PCT/JP2011/006452 |
371 Date: |
May 13, 2014 |
Current U.S.
Class: |
701/22 |
Current CPC
Class: |
Y02T 10/48 20130101;
F02N 2200/125 20130101; F02N 2200/061 20130101; Y02T 10/84
20130101; F02N 2200/0801 20130101; F02N 11/0837 20130101; Y02T
10/40 20130101; B60R 16/0236 20130101 |
Class at
Publication: |
701/22 |
International
Class: |
B60R 16/023 20060101
B60R016/023 |
Claims
1. A driving environment prediction device that predicts a driving
environment of a vehicle that causes a vehicle stop, the driving
environment prediction device comprising: a first vehicle stop time
rate calculator which is configured to calculate a rate of vehicle
stop time in a first period, as a first vehicle stop time rate; a
second vehicle stop time rate calculator which is configured to
calculate a rate of vehicle stop time in a second period which is
longer than the first period, as a second vehicle stop time rate;
and a driving environment predictor which is configured to predict
the driving environment, based on the first vehicle stop time rate
and the second vehicle stop time rate.
2. (canceled)
3. The driving environment prediction device according to claim 1,
wherein the driving environment is classification of whether a
vehicle driving area is an urban area or a suburban area, and the
driving environment predictor comprises: a first determining
section which is configured to determine whether the first vehicle
stop time rate is equal to or higher than a first reference value;
and a first specifying section which is configured to specify the
driving environment as the urban area when it is determined that
the first vehicle stop time rate is equal to or higher than the
first reference value by the first determining section.
4. The driving environment prediction device according to claim 3,
wherein the driving environment predictor further comprises: a
second determining section which is configured to determine whether
the second vehicle stop time rate is equal to or higher than a
second reference value which is smaller than the first reference
value; and a second specifying section which is configured to
specify the driving environment as the urban area when it is
determined that the second vehicle stop time rate is equal to or
higher than the second reference value by the second determining
section.
5. The driving environment prediction device according to claim 4,
wherein the driving environment predictor further comprises: a
third determining section which is configured to determine whether
the first vehicle stop time rate is less than a third reference
value which is smaller than the first reference value; a fourth
determining section which is configured to determine whether the
second vehicle stop time rate is less than a fourth reference value
which is smaller than the second reference value; and a third
specifying section which is configured to specify the driving
environment as the suburban area when it is determined that the
first vehicle stop time rate is less than the third reference value
by the third determining section and when it is determined that the
second vehicle stop time rate is less than the fourth reference
value by the fourth determining section.
6. A vehicle control device mounted on a vehicle having an engine
and a battery chargeable with an amount of electric power generated
by a generator which is driven with power of the engine, the
vehicle control device comprising: an idle reduction controller
which is configured to perform idle reduction control; an SOC
detector which is configured to detect a state of charge (SOC) of
the battery; an idle reduction capacity setting section which is
configured to set a capacity for idle reduction, which is expected
to be used in a stop and start period from an engine stop to an
engine restart by the idle reduction control, in an available SOC
range of the battery, during running of the vehicle; and a
remaining capacity controller which is configured to control the
amount of electric power generated by the generator, in order to
avoid a remaining capacity, which corresponds to the SOC detected
by the SOC detector, in the available SOC range from becoming less
than the capacity for idle reduction, during running of the
vehicle, wherein the idle reduction capacity setting section
comprises: a vehicle stop time rate calculator which is configured
to calculate a rate of vehicle stop time in a predetermined period;
and a capacity setting section which is configured to set the
capacity for idle reduction, based on the rate of vehicle stop
rate.
7. The vehicle control device according to claim 6, wherein the
vehicle stop time rate calculator comprises: a first vehicle stop
time rate calculator which is configured to calculate a rate of
vehicle stop time in a first period, as a first vehicle stop time
rate; and a second vehicle stop time rate calculator which is
configured to calculate a rate of vehicle stop time in a second
period which is longer than the first period, as a second vehicle
stop time rate, wherein the capacity setting section sets the
capacity for idle reduction, based on the first vehicle stop time
rate and the second vehicle stop time rate.
8. The vehicle control device according to claim 7, wherein the
capacity setting section comprises: a first determining section
which is configured to determine whether the first vehicle stop
time rate is equal to or higher than a first reference value; and a
first specifying section which is configured to, when it is
determined that the first vehicle stop time rate is equal to or
higher than the first reference value by the first determining
section, set the capacity for idle reduction to a larger value than
a capacity set when it is determined that the first vehicle stop
time rate is neither equal to nor higher than the first reference
value.
9. The vehicle control device according to claim 8, wherein the
capacity setting section further comprises: a second determining
section which is configured to determine whether the second vehicle
stop time rate is equal to or higher than a second reference value
which is smaller than the first reference value; and a second
specifying section which is configured to, when it is determined
that the second vehicle stop time rate is equal to or higher than
the second reference value by the second determining section, set
the capacity for idle reduction to a larger value than a capacity
set when it is determined that the second vehicle stop time rate is
neither equal to nor higher than the second reference value.
10. The vehicle control device according to claim 9, wherein the
idle reduction capacity setting section further comprises: a third
determining section which is configured to determine whether the
first vehicle stop time rate is less than a third reference value
which is smaller than the first reference value; a fourth
determining section which is configured to determine whether the
second vehicle stop time rate is less than a fourth reference value
which is smaller than the second reference value; and a third
specifying section which is configured to set the capacity for idle
reduction to a decreased value, when it is determined that the
first vehicle stop time rate is less than the third reference value
by the third determining section and when it is determined that the
second vehicle stop time rate is less than the fourth reference
value by the fourth determining section.
11. A driving environment prediction method of predicting a driving
environment of a vehicle that causes a vehicle stop, the driving
environment prediction method comprising: calculating a rate of
vehicle stop time in a first period, as a first vehicle stop time
rate; calculating a rate of vehicle stop time in a second period
which is longer than the first period, as a second vehicle stop
time rate; and predicting the driving environment, based on the
first vehicle stop time rate and the second vehicle stop time
rate.
12. A vehicle control method of controlling a vehicle having an
engine and a battery chargeable with an amount of electric power
generated by a generator which is driven with power of the engine,
the vehicle control method comprising the steps of: (a) performing
idle reduction control; (b) detecting a state of charge (SOC) of
the battery; (c) setting a capacity for idle reduction, which is
expected to be used in a stop and start period from an engine stop
to an engine restart by the idle reduction control, in an available
SOC range of the battery, during running of the vehicle; and (d)
controlling the amount of electric power generated by the
generator, in order to avoid a remaining capacity, which
corresponds to the SOC detected by the step (b), in the available
SOC range from becoming less than the capacity for idle reduction,
during running of the vehicle, wherein the step (c) comprises:
calculating a rate of vehicle stop time in a predetermined period;
and setting the capacity for idle reduction, based on the rate of
vehicle stop rate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a technology of predicting
a driving environment of a vehicle that causes a vehicle stop and a
technology of controlling a vehicle.
BACKGROUND ART
[0002] Accompanied with the requirement for improvement in fuel
consumption, automobiles performing idle reduction control have
recently drawn attention. In the automobile performing idle
reduction control, there is a proposed technique of increasing the
state of charge in a battery upon prediction of a traffic jam based
on traffic congestion prediction information by an automotive
navigation system (Patent Literature 1). An increase in number of
engine stops by idle reduction control in a traffic jam increases
consumption of the state of charge in the battery. The state of
charge in the battery is thus increased in advance, upon prediction
of a traffic jam.
[0003] The device of Patent Literature 1 is thought to predict a
traffic jam as the driving environment causing a vehicle stop,
which leads to an engine stop by idle reduction control. Another
proposed device predicts running in an urban area as the driving
environment causing a vehicle stop (Patent Literature 2). This
device predicts running in an urban area, based on the average
vehicle speed and the number of vehicle stops in a past given
time.
CITATION LIST
Patent Literatures
[0004] PTL 1: JP 2010-269712A [0005] PTL 2: JP 2002-356112A
[0006] The device described in Patent Literature 1, however,
requires the automotive navigation system and accordingly has a
problem of the complicated configuration. The device described in
Patent Literature 2, on the other hand, requires the relatively
long-time observation and accordingly has a problem of the poor
responsiveness.
SUMMARY OF INVENTION
Technical Problem
[0007] In order to solve the above problems, an object of the
invention is to predict a driving environment with high
responsiveness by a simple configuration.
Solution to Problem
[0008] The invention may be implemented by any of the following
aspects and embodiments, in order to solve at least part of the
above problems.
[Aspect 1]
[0009] There is provided a driving environment prediction device
that predicts a driving environment of a vehicle that causes a
vehicle stop. The driving environment prediction device comprises:
a vehicle stop time rate calculator which is configured to
calculate a rate of vehicle stop time in a predetermined period;
and a driving environment predictor which is configured to predict
the driving environment, based on the rate of vehicle stop
time.
[0010] The driving environment prediction device of this aspect
specifies the driving environment based on the rate of vehicle stop
time in the predetermined period. This aspect predicts the driving
environment with achieving both the responsiveness and the accuracy
by the simple configuration.
[Aspect 2]
[0011] There is provided the driving environment prediction device
according to Aspect 1, wherein the vehicle stop time rate
calculator comprises: a first vehicle stop time rate calculator
which is configured to calculate a rate of vehicle stop time in a
first period, as a first vehicle stop time rate; and a second
vehicle stop time rate calculator which is configured to calculate
a rate of vehicle stop time in a second period which is longer than
the first period, as a second vehicle stop time rate. The driving
environment predictor predicts the driving environment, based on
the first vehicle stop time rate and the second vehicle stop time
rate.
[0012] The driving environment prediction device of this aspect
specifies the driving environment, based on the first vehicle stop
time rate calculated in the first period which is the shorter
period between the first and second periods and the second vehicle
stop time rate calculated in the second period which is the longer
period. The first vehicle stop time rate is determined in the
shorter period, so that prediction based on the first vehicle stop
time rate enables the driving environment to be specified with high
responsiveness. The second vehicle stop time rate is determined in
the longer period, so that prediction based on the second vehicle
stop time rate enables the driving environment to be specified with
high accuracy. Accordingly, this aspect predicts the driving
environment with achieving both the responsiveness and the accuracy
by the simple configuration.
[Aspect 3]
[0013] There is provided the driving environment prediction device
according to Aspect 2, wherein the driving environment is
classification of whether a vehicle driving area is an urban area
or a suburban area. The driving environment predictor comprises: a
first determining section which is configured to determine whether
the first vehicle stop time rate is equal to or higher than a first
reference value; and a first specifying section which is configured
to specify the driving environment as the urban area when it is
determined that the first vehicle stop time rate is equal to or
higher than the first reference value by the first determining
section.
[0014] The driving environment prediction device of this aspect
allows for specification as an urban area with high responsiveness
by simply determining whether the first vehicle stop time rate is
equal to or higher than the first reference value.
[Aspect 4]
[0015] There is provided the driving environment prediction device
according to Aspect 3, wherein the driving environment predictor
further comprises: a second determining section which is configured
to determine whether the second vehicle stop time rate is equal to
or higher than a second reference value which is smaller than the
first reference value; and a second specifying section which is
configured to specify the driving environment as the urban area
when it is determined that the second vehicle stop time rate is
equal to or higher than the second reference value by the second
determining section.
[0016] The driving environment prediction device of this aspect
specifies the driving environment as an urban area, when the first
vehicle stop time rate is equal to or higher than the first
reference value or when the second vehicle stop time rate is equal
to or higher than the second reference value. This allows for the
quicker specification and thereby ensures prediction with high
responsiveness.
[Aspect 5]
[0017] There is provided the driving environment prediction device
according to either Aspect 3 or Aspect 4, wherein the driving
environment predictor further comprises: a third determining
section which is configured to determine whether the first vehicle
stop time rate is less than a third reference value which is
smaller than the first reference value; a fourth determining
section which is configured to determine whether the second vehicle
stop time rate is less than a fourth reference value which is
smaller than the second reference value; and a third specifying
section which is configured to specify the driving environment as
the suburban area when it is determined that the first vehicle stop
time rate is less than the third reference value by the third
determining section and when it is determined that the second
vehicle stop time rate is less than the fourth reference value by
the fourth determining section.
[0018] The driving environment prediction device of this aspect
provides hysteresis in classification between an urban area and a
suburban area, thereby preventing hunting in result of
prediction.
[Aspect 6]
[0019] There is provided a vehicle control device mounted on a
vehicle having an engine and a battery chargeable with an amount of
electric power generated by a generator which is driven with power
of the engine. The vehicle control device comprises: an idle
reduction controller which is configured to perform idle reduction
control; an SOC detector which is configured to detect a state of
charge (SOC) of the battery; an idle reduction capacity setting
section which is configured to set a capacity for idle reduction,
which is expected to be used in a stop and start period from an
engine stop to an engine restart by the idle reduction control, in
an available SOC range of the battery, during running of the
vehicle; and a remaining capacity controller which is configured to
control the amount of electric power generated by the generator, in
order to avoid a remaining capacity, which corresponds to the SOC
detected by the SOC detector, in the available SOC range from
becoming less than the capacity for idle reduction, during running
of the vehicle. The idle reduction capacity setting section
comprises: a vehicle stop time rate calculator which is configured
to calculate a rate of vehicle stop time in a predetermined period;
and a capacity setting section which is configured to set the
capacity for idle reduction, based on the rate of vehicle stop
rate.
[0020] The vehicle control method of this aspect enables the
capacity for idle reduction to be adequately determined in the
available SOC range of the battery by taking into account the
driving environment of the vehicle that causes a vehicle stop.
[Aspect 7]
[0021] There is provided the vehicle control device according to
Aspect 6, wherein the vehicle stop time rate calculator comprises:
a first vehicle stop time rate calculator which is configured to
calculate a rate of vehicle stop time in a first period, as a first
vehicle stop time rate; and a second vehicle stop time rate
calculator which is configured to calculate a rate of vehicle stop
time in a second period which is longer than the first period, as a
second vehicle stop time rate. The capacity setting section sets
the capacity for idle reduction, based on the first vehicle stop
time rate and the second vehicle stop time rate.
[0022] The vehicle control device of this aspect enables the
capacity for idle reduction to be more adequately determined in the
available SOC range of the battery.
[Aspect 8]
[0023] There is provided the vehicle control device according to
Aspect 7, wherein the capacity setting section comprises: a first
determining section which is configured to determine whether the
first vehicle stop time rate is equal to or higher than a first
reference value; and a first specifying section which is configured
to, when it is determined that the first vehicle stop time rate is
equal to or higher than the first reference value by the first
determining section, set the capacity for idle reduction to a
larger value than a capacity set when it is determined that the
first vehicle stop time rate is neither equal to nor higher than
the first reference value.
[0024] The vehicle control device of this aspect increases the
capacity for idle reduction when it is determined that the first
vehicle stop time rate is equal to or higher than the first
reference value. This results in more adequately determining the
capacity for idle reduction.
[Aspect 9]
[0025] There is provided the vehicle control device according to
Aspect 8, wherein the capacity setting section further comprises: a
second determining section which is configured to determine whether
the second vehicle stop time rate is equal to or higher than a
second reference value which is smaller than the first reference
value; and a second specifying section which is configured to, when
it is determined that the second vehicle stop time rate is equal to
or higher than the second reference value by the second determining
section, set the capacity for idle reduction to a larger value than
a capacity set when it is determined that the second vehicle stop
time rate is neither equal to nor higher than the second reference
value.
[0026] The vehicle control device of this aspect increases the
capacity for idle reduction when it is determined that the second
vehicle stop time rate is equal to or higher than the second
reference value which is smaller than the first reference value.
This results in more adequately determining the capacity for idle
reduction.
[Aspect 10]
[0027] There is provided the vehicle control device according to
either Aspect 8 or Aspect 9, wherein the idle reduction capacity
setting section further comprises: a third determining section
which is configured to determine whether the first vehicle stop
time rate is less than a third reference value which is smaller
than the first reference value; a fourth determining section which
is configured to determine whether the second vehicle stop time
rate is less than a fourth reference value which is smaller than
the second reference value; and a third specifying section which is
configured to set the capacity for idle reduction to a decreased
value, when it is determined that the first vehicle stop time rate
is less than the third reference value by the third determining
section and when it is determined that the second vehicle stop time
rate is less than the fourth reference value by the fourth
determining section.
[0028] The vehicle control device of this aspect reduces the
capacity for idle reduction, when it is determined that the first
vehicle stop time rate is less than the third reference value which
is smaller than the first reference value and when it is determined
that the second vehicle stop time rate is less than the fourth
reference value which is smaller than the second reference value.
This results in more adequately determining the capacity for idle
reduction, while preventing hunting in control of the capacity for
idle reduction.
[Aspect 11]
[0029] There is provided a driving environment prediction method of
predicting a driving environment of a vehicle that causes a vehicle
stop. The driving environment prediction method comprises:
calculating a rate of vehicle stop time in a predetermined period;
and predicting the driving environment, based on the rate of
vehicle stop time.
[0030] The driving environment prediction method of this aspect
predicts the driving environment with achieving both the
responsiveness and the prediction accuracy, like the driving
environment prediction device of Aspect 1.
[Aspect 12]
[0031] There is provided a vehicle control method of controlling a
vehicle having an engine and a battery chargeable with an amount of
electric power generated by a generator which is driven with power
of the engine. The vehicle control method comprises the steps of:
(a) performing idle reduction control; (b) detecting a state of
charge (SOC) of the battery; (c) setting a capacity for idle
reduction, which is expected to be used in a stop and start period
from an engine stop to an engine restart by the idle reduction
control, in an available SOC range of the battery, during running
of the vehicle; and (d) controlling the amount of electric power
generated by the generator, in order to avoid a remaining capacity,
which corresponds to the SOC detected by the SOC detector, in the
available SOC range from becoming less than the capacity for idle
reduction, during running of the vehicle. The step (c) comprises:
calculating a rate of vehicle stop time in a predetermined period;
and setting the capacity for idle reduction, based on the rate of
vehicle stop rate.
[0032] The vehicle control method of this aspect enables the
capacity for idle reduction to be determined adequately in the
available SOC range of the battery, like the vehicle control device
of Aspect 5.
[0033] The invention may be implemented by any of various aspects
other than those described above. For example, the invention may be
configured as: a vehicle equipped with the driving environment
prediction device according to any one of Aspects 1 to 5; a vehicle
equipped with the vehicle control device according to any one of
Aspects 6 to 10; a driving environment prediction method including
steps corresponding to the respective components included in the
driving environment prediction device according to any one of
Aspects 2 to 5; a vehicle control method including steps
corresponding to the respective components included in the vehicle
control device according to any one of Aspects 6 to 10; a computer
program that causes a computer to perform the respective steps
included in the driving environment prediction method according to
Aspect 11; and a computer program that causes a computer to perform
the respective steps included in the vehicle control method
according to Aspect 12.
BRIEF DESCRIPTION OF DRAWINGS
[0034] FIG. 1 is a diagram illustrating the configuration of an
automobile 200 according to an embodiment of the invention;
[0035] FIG. 2 is a diagram illustrating the functional
configuration of an ECU 50;
[0036] FIG. 3 is a flowchart showing a target SOC estimation
routine;
[0037] FIG. 4 is a diagram illustrating an SOC distribution request
level calculation map MP;
[0038] FIG. 5 is a diagram illustrating a target SOC calculation
table TB;
[0039] FIG. 6 is a diagram illustrating time charts of vehicle
speed and SOC during operation of the automobile;
[0040] FIG. 7 is a flowchart showing a driving environment
prediction routine;
[0041] FIG. 8 is a diagram illustrating a time chart showing the
relationship between vehicle speed V and start time of a vehicle
stop time obtaining routine and a vehicle stop time rate
calculation routine;
[0042] FIG. 9 is a flowchart showing the vehicle stop time
obtaining routine;
[0043] FIG. 10 is a diagram illustrating one example of a first
storage stack ST1;
[0044] FIG. 11 is a diagram illustrating a change in storage of the
first storage stack ST1;
[0045] FIG. 12 is a diagram illustrating one example of a second
storage stack ST2;
[0046] FIG. 13 is a flowchart showing the vehicle stop time rate
calculation routine;
[0047] FIG. 14 is a flowchart showing an urban area/suburban area
determination routine;
[0048] FIG. 15 is a graph showing frequency distributions of a
shorter-period vehicle stop time rate RS in the urban area and in
the suburban area;
[0049] FIG. 16 is a graph showing frequency distributions of a
longer-period vehicle stop time rate RL in the urban area and in
the suburban area; and
[0050] FIG. 17 is a diagram showing the relationship between a
reference value (R1, R2) for specifying a change from a suburban
area to an urban area and a reference value (R3, R2) for specifying
a change from an urban area to a suburban area.
DESCRIPTION OF EMBODIMENTS
[0051] Some aspects of the invention are described below with
reference to embodiments in the following sequence:
A. General Configuration
B. Configuration of ECU
C. Configuration of Target SOC Estimator
D. Driving Environment Prediction Method
E. Advantageous Effects of Embodiment
F. Modifications
A. General Configuration
[0052] FIG. 1 is a diagram illustrating the configuration of an
automobile 200 according to an embodiment of the invention. The
automobile 200 is a vehicle having idle reduction function. The
automobile 200 includes an engine 10, an automatic transmission 15,
a differential gear 20, drive wheels 25, a starter 30, an
alternator 35, a battery 40 and an electronic control unit (ECU)
50.
[0053] The engine 10 is an internal combustion engine that
generates power by combustion of a fuel such as gasoline or light
oil. The power of the engine 100 is transmitted to the automatic
transmission 15, while being transmitted to the alternator 35 via a
drive mechanism 34. The output of the engine 10 is changed by an
engine control computer (not shown) according to the pressure of an
accelerator pedal (not shown) stepped on by the driver.
[0054] The automatic transmission 15 automatically changes the gear
ratio (so-called gear shifting). The power (rotation speedtorque)
of the engine 10 is subjected to gear shifting by the automatic
transmission 15 and is transmitted as a desired rotation
speedtorque via the differential gear 20 to the left and right
drive wheels 25. The power of the engine 10 is changed according to
the accelerator pedal pressure and is transmitted via the automatic
transmission 15 to the drive wheels 25 to accelerate or decelerate
the vehicle (automobile 200).
[0055] This embodiment employs a belt drive configuration as the
drive mechanism 34 transmitting the power of the engine 10 to the
alternator 35. The alternator 35 uses part of the power of the
engine 10 to generate electric power. The alternator 35 is a type
of generator. The generated electric power is used to charge the
battery 40 via an inverter (not shown). In the description hereof,
power generation by the alternator 35 using the power of the engine
10 is called "fuel power generation".
[0056] The battery 40 is a lead acid battery serving as a DC power
source for a voltage of 14 V and supplies electric power to
peripheral devices provided other than the engine main body. In the
description hereof, the peripheral devices provided other than the
engine main body and operated with electric power of the battery 40
are called "auxiliary machines". The group of auxiliary machines is
called "auxiliary machinery". The automobile 200 includes, for
example, head lights 72 and an air conditioner (A/C) 74 as the
auxiliary machinery 70.
[0057] The starter 30 is a self starter to start the engine 10 with
electric power supplied from the battery 40. In general, when the
driver operates an ignition switch (not shown) to start driving an
automobile at a stop, the starter 30 is activated to start the
engine 10. This starter 30 is used to restart the engine 10 in the
no idling state as described later. In the description hereof, the
no idling state means the engine stop state by idle reduction
control.
[0058] The ECU 50 includes a CPU that performs computer programs, a
ROM that stores computer programs and others, a RAM that
temporarily stores data and input/output ports connected with, for
example, various sensors and actuators. The sensors connected with
the ECU 50 include: a wheel speed sensor 82 that detects the
rotation speed of the drive wheels 25; a brake pedal sensor 84 that
detects depression or non-depression of a brake pedal (not shown):
an accelerator opening sensor 86 that detects the pressure of an
accelerator pedal (not shown) as an accelerator opening; a battery
current sensor 88 that detects the charge-discharge current of the
battery 40; and an alternator current sensor 89 that detects the
output current of the alternator 35. The actuators include the
starter 30 and the alternator 35. The ECU 50 receives the supply of
electric power from the battery 40.
[0059] The ECU 50 controls the starter 30 and the alternator 35
based on signals from the various sensors mentioned above and an
engine control computer (not shown), so as to control engine stops
and restarts (idle reduction control) and control the SOC of the
battery 40.
B. Configuration of ECU
[0060] FIG. 2 is a diagram illustrating the functional
configuration of the ECU 50. As illustrated, the ECU 50 includes an
idle reduction controller 90 and an SOC controller 100. The
functions of the idle reduction controller 90 and the SOC
controller 100 are actually implemented by the CPU included in the
ECU 50 executing the computer programs stored in the ROM.
[0061] The idle reduction controller 90 obtains a wheel speed Vh
detected by the wheel speed sensor 82 and an accelerator opening Tp
detected by the accelerator opening sensor 86 and outputs an
instruction Ss to stop/start the engine 10 to the starter 30. More
specifically, the idle reduction controller 90 determines that an
engine stop condition is satisfied and outputs an engine stop
instruction Ss to the starter 30, when the wheel speed Vh is
reduced below a predetermined speed (for example, 10 km/h). The
idle reduction controller 90 determines that an engine restart
condition is satisfied and outputs an engine restart instruction Ss
to the starter 30, when depression of the accelerator pedal is
subsequently detected based on the accelerator opening Tp.
[0062] In other words, the idle reduction controller 90 stops the
engine 10 when the engine stop condition is satisfied, and restarts
the engine 10 when the engine restart condition is satisfied after
the engine stop. The engine stop condition and the engine restart
condition are not limited to those described above. For example,
the engine stop condition may be that the wheel speed Vh is fully
reduced to 0 km/h, and the engine restart condition may be that the
driver releases the brake pedal.
[0063] The SOC controller 100 includes a target SOC estimator 110,
a battery SOC calculator 120 and a feedback controller 130. The
target SOC estimator 110 estimates an SOC expected to be used
during a time period from an engine stop to an engine restart
(hereinafter called "stop and start period") by idle reduction
control during vehicle running (for example, when the wheel speed
Vh>0 km/h), as a target SOC (hereinafter also called "target SOC
value") C1. The detailed configuration will be described in Chapter
C. The "SOC" herein is defined as a value obtained by dividing the
electric charge remaining in the battery by the electric charge
accumulated in the battery in the fully charged state.
[0064] The battery SOC calculator 120 calculates a current SOC
(hereinafter called "present SOC value") C2 of the battery 40,
based on charge-discharge current (called "battery current") Ab of
the battery 40 detected by the battery current sensor 88. More
specifically, the battery SOC calculator 120 calculates the present
SOC value C2 by integrating the charge-discharge currents Ab with
setting the charge currents of the battery 40 to positive values
and setting the discharge currents of the battery 40 to negative
values. The configuration of the battery current sensor 88 and the
battery SOC calculator 120 corresponds to the "SOC detector"
described in [Solution to Problem]. The SOC detector is not
necessarily limited to the configuration that makes a calculation
based on the battery current detected by the battery current sensor
88 but may be configured to make a calculation based on, for
example, a battery electrolytic solution specific gravity sensor, a
cell voltage sensor or a battery terminal voltage sensor. Moreover,
the SOC detector is not necessarily limited to the configuration
that detects the electric charge remaining in the battery but may
be configured to detect the state of charge using another
parameter, for example, a chargeable amount.
[0065] The feedback controller 130 calculates a difference by
subtracting the present SOC value C2 from the target SOC value C1
during vehicle running and determines a voltage command value Sv
that makes the calculated difference equal to a value 0 by feedback
control. This voltage command value Sv indicates the amount of
power to be generated by the alternator 35 and is sent to the
alternator 35. As a result, the present SOC value C2 is controlled
to the target SOC value C1 by fuel power generation.
[0066] The SOC controller 100 has a function called "battery
control" and a function called "charge control", in addition to the
above functions, although not specifically illustrated. The
following describes battery control. The battery or more
specifically the lead acid battery of the embodiment has a
predetermined available SOC range (operable SOC range) based on the
need for prolonged life. Accordingly, the "battery control" is
performed to increase the power of the engine 10 and thereby
increase the SOC into the above SOC range when the SOC of the
battery 40 becomes lower than a lower limit (for example, 60%) of
this SOC range and to consume the SOC and thereby decrease the SOC
into the above SOC range when the SOC exceeds an upper limit (for
example, 90%) of the SOC range. When the SOC becomes lower than the
lower limit during an engine stop by idle reduction control, the
engine is restarted to increase the SOC into the above SOC range by
fuel power generation.
[0067] The "charge control" is a control process that suppresses
the battery from being charged by fuel power generation during
normal running to save fuel consumption and charges the battery by
regenerative power generation during deceleration running. The
charge control is a known configuration and is thus not
specifically described here, but basically performs the following
operations. In the charge control, feedback control by the feedback
controller 130 during normal running is performed when the target
SOC value C1 is greater than the present SOC value C2; a specified
power generation cutoff voltage is set to the voltage command value
Sv, which is given to the alternator 35, when the target SOC value
C1 is equal to or less than the present SOC value C2. This
configuration suppresses charging during normal running and saves
fuel consumption. The "normal running" herein denotes the state of
the automobile 200 other than "vehicle stop" when the vehicle speed
is 0 km/h and "deceleration running" when the regenerative power
generation described above is performed.
C. Configuration of Target SOC Estimator
[0068] The target SOC estimator 110 includes a driving environment
predictor 112, a vehicle state predictor 114, an SOC distribution
request level calculator 116 and a target SOC calculator 118.
[0069] The driving environment predictor 112 predicts the driving
environment of the vehicle. According to this embodiment, the
"driving environment" shows whether a future (from now) vehicle
driving area will be an urban area or a suburban area. The driving
environment predictor 112 determines whether the driving
environment up to now is an urban area or a suburban area based on
the wheel speed Vh detected by the wheel speed sensor 82 and
outputs the result of determination as an urban area/suburban area
classification P1 of a future (from now) driving area. The urban
area/suburban area classification P1 may take a value 1 in the case
of an urban area and a value 0 in the case of a suburban area. The
detailed procedure of determining whether the driving environment
is an urban area or a suburban area will be described later in
Chapter D.
[0070] The vehicle state predictor 114 predicts the state of the
automobile 200 (vehicle state). The "vehicle state" herein is a
parameter indicating how much SOC the automobile 200 is expected to
consume hereafter. More specifically, the vehicle state predictor
114 calculates the amount of electric power consumed by the
auxiliary machinery 70 based on the battery current Ab detected by
the battery current sensor 88 and an alternator current Aa detected
by the alternator current sensor 89 and outputs the calculated
amount of electric power as a vehicle state P2. The SOC consumption
rate increases with an increase in amount of electric power
consumed by the auxiliary machinery 70. According to the
embodiment, the vehicle state predictor 114 thus predicts the
amount of electric power consumed by the auxiliary machinery 70 as
the vehicle state P2.
[0071] The embodiment predicts the vehicle state P2 based on the
amount of electric power consumed by the auxiliary machinery 70,
but the invention is not limited to this configuration. For
example, the vehicle state P2 may be predicted, based on
air-conditioning information (for example, a difference between a
target temperature and vehicle interior temperature) relating to
the power consumption of the air-conditioner (A/C) or based on
information regarding the engine warm-up state such as a difference
between engine water temperature and ambient temperature. The
invention is not limited to the configuration of predicting the
vehicle state P2 based on one parameter selected among the amount
of electric power consumed by the auxiliary machinery 70, the
air-conditioning information and the warm-up state information, but
may be implemented by a configuration that determines the vehicle
state P2 based on two or more parameters. In the case of using two
or more parameters, the application is preferably configured to
predict the vehicle state P2 by multiplying the respective
parameters by individual weighting factors.
[0072] Moreover, each of the configurations described above
determines the current operating state of the auxiliary machinery
based on the currently detected sensor signals and regards the
current operating state as the future vehicle state. An alternative
configuration may read a sign of change in operating state from the
current operating state determined as described above, so as to
predict the future vehicle state.
[0073] The driving environment predictor 112 and the vehicle state
predictor 114 of the above configuration continually perform the
predictions after the automobile 200 starts operation. The
respective components 122 to 124 are actually implemented by the
CPU included in the ECU 50 executing the computer programs stored
in the ROM. The urban area/suburban area classification P1
predicted by the driving environment predictor 112 and the vehicle
state P2 predicted by the vehicle state predictor 114 are sent to
an SOC distribution request level calculator 116.
[0074] The SOC distribution request level calculator 116 calculates
an SOC distribution request level P3 based on the urban
area/suburban area classification P1 and the vehicle state P2. The
target SOC calculator 118 calculates a target SOC value C1 based on
the SOC distribution request level P3. The following describes the
detailed processes of the SOC distribution request level calculator
116 and the target SOC calculator 118.
[0075] FIG. 3 is a flowchart showing a target SOC estimation
routine. This target SOC estimation routine is performed repeatedly
at predetermined time intervals (for example, 60 sec) during
vehicle running. In other words, the target SOC estimation routine
is not performed during a stop of the engine 10 by idle reduction
control. As illustrated, when the process flow starts, the CPU of
the ECU 50 obtains the urban area/suburban area classification P1
predicted by the driving environment predictor 112 (FIG. 2) (step
S100) and also obtains the vehicle state P2 predicted by the
vehicle state predictor 114 (FIG. 2) (step S200).
[0076] After execution of step S200, the CPU calculates an SOC
distribution request level based on the urban area/suburban area
classification P1 and the vehicle state P2 by using an SOC
distribution request level calculation map MP (step S300). The
available SOC range is set for each type of battery as described
above. The procedure of the embodiment distributes the available
SOC range into an SOC range for idle reduction and an SOC range for
charge control. The "SOC distribution request level" herein is a
parameter specifying the level of the above distribution.
[0077] FIG. 4 is a diagram illustrating the SOC distribution
request level calculation map MP. As illustrated, the SOC
distribution request level calculation map MP has the urban
area/suburban area classification P1 as abscissa and the vehicle
state P2 as ordinate and stores map data to map the SOC
distribution request level P3 related to the value on the abscissa
and the value on the ordinate. The SOC distribution request level
calculation map MP is created by determining the relationship of
the SOC distribution request level P3 to the urban area/suburban
area classification P1 and the vehicle state P2 in advance
experimentally or by simulation and is stored in the ROM. The
process of step S300 reads the SOC distribution request level
calculation map MP from the ROM and refers to this map MP to obtain
the SOC distribution request level P3 related to the urban
area/suburban area classification P1 obtained at step S100 and the
vehicle state P2 obtained at step S200. In the illustrated example,
four value, A, B, C and D are provided as the SOC distribution
request level P3. The values descend in the order of D, C, B and A.
The urban area/suburban area classification P1 equal to the value 1
representing the urban area has the higher SOC distribution request
level P3, compared with the urban area/suburban area classification
P1 equal to the value 0 representing the suburban area.
Additionally, the SOC distribution request level P3 increases with
an increase in vehicle state P2.
[0078] Referring back to FIG. 3, after execution of step S300, the
CPU calculates the target SOC value C1 based on the SOC
distribution request level P3 by using a target SOC calculation
table TB (step S400).
[0079] FIG. 5 is a diagram illustrating the target SOC calculation
table TB. As illustrated, the target SOC calculation table TB has
the SOC distribution request level P3 as abscissa and the target
SOC value C1 as ordinate and shows the relationship of the target
SOC value C1 to the SOC distribution request level P3 by a linear
line L. The target SOC calculation table TB is created by
determining the relationship of the target SOC value C1 to the SOC
distribution request level P3 in advance experimentally or by
simulation and is stored in the ROM. The process of step S400 reads
the target SOC calculation table TB from the ROM and refers to this
table TB to obtain the target SOC value C1 related to the SOC
distribution request level P3 calculated at step S300.
[0080] As illustrated, the target SOC value C1 shown by the linear
line L is a value set in an available SOC range W of the battery 40
and indicates a distribution rate when the available SOC range W is
distributed into a capacity for charge control and a capacity for
idle reduction. More specifically, the area of the capacity for
idle reduction is set on the lower side of the available SOC range
W of the battery 40, and the area of the capacity for charge
control is set on the upper side. The boundary between these two
areas shows the target SOC value C1. In other words, the level
determined by adding the capacity for idle reduction to the lower
limit of the available SOC range W is set as the target SOC value
C1.
[0081] The capacity for charge control is a battery capacity
required due to suppression of fuel power generation by the charge
control described above. The capacity for idle reduction is a
capacity expected to be used in the future stop and start period.
According to this embodiment, the capacity for idle reduction is
set to an expected maximum capacity. The capacity for idle
reduction increases with an increase in SOC distribution request
level P3. When the SOC is controlled to the upper side of the
linear line L, the remaining capacity corresponding to the SOC in
the available SOC range exceeds the capacity for idle reduction.
This causes the idle reduction control to be fully implemented and
further has an excess corresponding to the exceeding capacity. The
target SOC value C1 shown by the linear line L accordingly
indicates the SOC that enables idle reduction control to be fully
implemented hereafter and minimizes the amount of power generation
for accumulation of SOC.
[0082] The target SOC value C1 linearly increases with an increase
in SOC distribution request level P3 as shown by the linear line L.
The invention is, however, not limited to this example. For
example, the target SOC value C1 may be configured to linearly
increase with an increase in SOC distribution request level P3 when
the SOC distribution request level P3 is equal to or less than a
predetermined value and to maintain a fixed value when the SOC
distribution request level P3 is greater than the predetermined
value. This configuration is effective for a battery having a
relatively narrow available SOC range. Additionally, a change in
target SOC value C1 may be shown by a curved line, instead of the
linear line.
[0083] Referring back to FIG. 3, after execution of step S400, the
CPU outputs the target SOC value C1 calculated at step S400 to the
feedback controller 130 (step S500) and subsequently terminates the
target SOC estimation routine. The feedback controller 130 (FIG. 2)
controls the present SOC value C2 to the calculated target SOC
value C1. The present SOC value C2 indicates the remaining capacity
in the available SOC range of the battery 40. The control described
above results in avoiding the remaining capacity from becoming less
than the capacity for idle reduction during vehicle running. More
specifically, when the present SOC value is located in the area of
the capacity for charge control in FIG. 5, i.e., when the remaining
capacity is greater than the capacity for idle reduction, charge
control is performed to suppress the battery 40 from being charged
by fuel power generation. When the SOC decreases and is becoming
less than the capacity for idle reduction, the SOC is controlled to
the target SOC value C1 shown by the linear line L by fuel power
generation. Such control accordingly prevents the SOC from becoming
less than the capacity for idle reduction.
[0084] FIG. 6 is a diagram illustrating time charts of vehicle
speed and SOC (present SOC value C2) of the battery 40 during
operation of the automobile 200. The time charts have the vehicle
speed and the SOC as the ordinate and the time as the abscissa.
When the operation of the automobile 200 is started and the
automobile 200 starts moving at a time t0, the vehicle speed
gradually increases to normal running. The vehicle then shifts to
the deceleration state at a time t1. In a t0-t1 period from the
time t0 to the time t1, the SOC gradually decreases as shown by the
solid line. This solid line, however, indicates a change according
to the prior art, and this embodiment has a change as shown by the
two-dot chain line. This is described below.
[0085] After the time t1, the vehicle stops at a time t2. In a
t1-t2 period, the SOC gradually increases as shown by the solid
line by regenerative power generation during deceleration. A period
from the time t2 (more specifically, at the time when the engine
stop condition is satisfied) to a time t3 when the vehicle speed
has a rise is a stop and start period SST, when the engine 10 is at
stop. In the stop and start period SST, the SOC gradually decreases
by power consumption of the auxiliary machinery. According to the
prior art, as shown by the solid line, when the SOC decreases to a
lower limit SL during this engine stop (time tb), battery control
is performed to restart the engine 10. After the engine restart,
the SOC increases by power generation using the power of the engine
10, as shown by the solid line.
[0086] According to the embodiment, when the SOC decreases during
normal running and causes the remaining capacity in the available
SOC range of the battery 40 to become less than the capacity for
idle reduction (time ta), the SOC is increased by fuel power
generation. As shown by the two-dot chain line in illustration, the
SOC increases in a ta-t2 period. This increase is in view of the
maximum battery capacity expected to be used in the future stop and
start period, so that the SOC decreasing in the stop and start
period t2-t3 does not reach the lower limit SL. The "future stop
and start period" is not limited to one stop and start period SST
as illustrated but includes all a plurality of stop and start
periods within a predetermined time period. According to the
embodiment, the engine 10 is restarted in the state that the SOC
does not decrease to the lower limit in the stop and start period
t2-t3, unlike the prior art.
D. Driving Environment Prediction Method
[0087] FIG. 7 is a flowchart showing a driving environment
prediction routine. The CPU of the ECU 50 executes the driving
environment prediction routine to implement the driving environment
predictor 112 (FIG. 2). As illustrated, when the process flow
starts, the CPU of the ECU 50 first determines whether key-on
start-up is performed (step S610). Herein "key-on start-up" means
that the engine is started by the driver's operation of an ignition
key (not shown). When it is determined that no key-on start-up is
performed at step S610, the process flow repeats the determination
of step S610 and waits for key-on start-up. When key-on start-up is
performed, the CPU performs an initialization operation to clear
storage stacks and variables described later (step S620).
[0088] The CPU subsequently specifies the wheel speed Vh detected
by the wheel speed sensor 82 as the vehicle speed V and determines
whether the vehicle speed V is higher than a predetermined speed V0
(for example, 15 km/h) (step S630). When the vehicle speed V is
equal to or lower than V0, the CPU waits until the vehicle speed V
exceeds V0 and then proceeds to step S640. Instead of using the
detected value of the wheel speed sensor 82, the detected value of
a vehicle speed sensor (not shown) may be used as the vehicle
speed. At step S640, the CPU starts a vehicle stop time obtaining
routine and a vehicle stop time rate calculation routine described
below.
[0089] FIG. 8 is a diagram illustrating a time chart showing the
relationship between the vehicle speed V and the start time of the
vehicle stop time obtaining routine and the vehicle stop time rate
calculation routine. The time chart has the time t as abscissa and
the vehicle speed V as the ordinate. As illustrated, key-on
start-up is performed at a time t1, and the vehicle speed keeps 0
km/h for a predetermined time period from the key-on start-up,
because of reasons like catalyst warm-up. The vehicle speed V
subsequently has a rise and reaches a specified speed V0 at a time
t2, when the vehicle stop time obtaining routine and the vehicle
stop time rate calculation routine are started. This configuration
is for the purpose of not counting a period (t1-t2) from the key-on
start-up time to the time when the vehicle speed V reaches the
specified speed V0 as a vehicle stop time obtained by the vehicle
stop time obtaining routine.
[0090] Referring back to FIG. 7, after execution of step S640, the
CPU determines whether a start restriction time (TL described
later) has elapsed after the vehicle speed V reaches V0 (step
S650). The CPU waits for elapse of the start restriction time TL
and performs an urban area/suburban area determination routine
described later (step S660). After execution of step S660, the CPU
determines whether the driver switches off the ignition key (step
S670). The process flow repeats step S660 until the driver's
key-off operation. In response to the driver's key-off operation,
the CPU terminates this driving environment prediction routine.
[0091] FIG. 9 is a flowchart showing the vehicle stop time
obtaining routine started at step S640. When the process flow
starts, the CPU repeatedly performs a vehicle stop time obtaining
process described below at a first cycle G1 (step S710). This
vehicle stop time obtaining process calculates a vehicle stop time
in a period of the first cycle G1 and stores the calculated vehicle
stop time into a first storage stack ST1. The first cycle G1 is 60
[sec].
[0092] FIG. 10 is a diagram illustrating one example of the first
storage stack ST1. As illustrated, the first storage stack ST1
consists of ten stack elements M(1), M(2), . . . , M(10). At step
S710, the CPU calculates the vehicle stop time within 60 seconds at
every 60 seconds and sequentially stores the results of calculation
into the stack elements M(n) of the first storage stack ST1, where
n represents variables from 1 to 10 and the stack element M(n) in
which the result of calculation is stored shifts from M(1) to
M(10). The procedure of calculating the vehicle stop time
determines whether the vehicle is at stop (Vh=0 km/h) based on the
wheel speed Vh detected by the wheel speed sensor 82 and measures
the vehicle stop time over the period of the first cycle G1.
Instead of using the detected value of the wheel speed sensor 82,
the detected value of a vehicle speed sensor (not shown) may be
used to determine whether the vehicle is at stop.
[0093] More specifically, at step S710, the CPU sequentially
calculates the vehicle stop time during the period of 60 seconds at
the cycle of 60 seconds and sequentially stores the calculated
vehicle stop time one by one into the stack elements M(1) to M(10).
In the illustrated example, after elapse of 60 seconds, the vehicle
stop time of 20 seconds is stored into the stack element M(1);
after elapse of 120 seconds, the vehicle stop time of 0 second is
stored into the stack element M(2); and after elapse of 180
seconds, the vehicle stop time of 60 seconds is stored into the
stack element M(3). In this way, the vehicle stop time is
sequentially stored at the cycle of 60 seconds. As shown in FIG.
11, when the storage of the vehicle stop time occupies the last
stack element M(10), i.e., when the total of 10 minutes (600
seconds) have elapsed, a vehicle stop time pt calculated in a next
cycle is stored in the first stack element M(1). At this moment,
the existing storages are kept in the other stack elements M(2) to
M(10). A vehicle stop time (not shown) calculated in a next cycle
is stored in the second stack element M(2). In this manner, when
all the stack elements M(10) have been occupied, the storages in
the stack elements have sequentially been updated one by one from
the top.
[0094] Referring back to FIG. 9, the CPU repeatedly performs a
vehicle stop time obtaining process described below at a second
cycle G2 (step S720). This vehicle stop time obtaining process
calculates a vehicle stop time in a period of the second cycle G2
and stores the calculated vehicle stop time into a second storage
stack ST2. The second cycle G2 is 90 [sec]. Although the process of
step S720 is illustrated as if subsequent to step S710, this is for
convenience of illustration. Actually, like the process of step
S710 described above, the process of step S720 is performed
immediately after start of the vehicle stop time obtaining routine.
In other words, the process of step S710 and the process of step
S720 are performed in parallel by time sharing.
[0095] FIG. 12 is a diagram illustrating one example of the second
storage stack ST2. As illustrated, the second storage stack ST2
consists of ten stack elements N(1), N(2), . . . , N(10). At step
S720, the CPU calculates the vehicle stop time within 90 seconds at
every 90 seconds and sequentially stores the results of calculation
into the stack elements N(n) of the second storage stack ST2, where
n represents variables from 1 to 10 and the stack element N(n) in
which the result of calculation is stored shifts from N(1) to
N(10). The procedure of calculating the vehicle stop time detects a
vehicle stop based on the wheel speed Vh detected by the wheel
speed sensor 82 as described above and measures the vehicle stop
time over a period of the second cycle G2.
[0096] More specifically, at step S720, the CPU sequentially
calculates the vehicle stop time during the period of 90 seconds at
the cycle of 90 seconds and sequentially stores the calculated
vehicle stop time one by one into the stack elements N(1) to N(10).
In the illustrated example, after elapse of 90 seconds, the vehicle
stop time of 20 seconds is stored into the stack element N(1);
after elapse of 180 seconds, the vehicle stop time of 0 second is
stored into the stack element N(2); and after elapse of 270
seconds, the vehicle stop time of 0 second is stored into the stack
element N(3). In this way, the vehicle stop time is sequentially
stored at the cycle of 90 seconds. When the storage of the vehicle
stop time occupies the last stack element N(10), i.e., when the
total of 15 minutes (900 seconds) have elapsed, the storages in the
stack elements have sequentially been updated one by one from the
top, like the first storage stack ST1.
[0097] FIG. 13 is a flowchart showing the vehicle stop time rate
calculation routine started at step S640 (FIG. 7). When the process
flow starts, the CPU repeatedly calculates a shorter-period vehicle
stop time rate RS at the first cycle G1 after elapse of 10 minutes
since the start of processing (step S810). More specifically, the
CPU calculates the total value of the respective values stored in
the stack elements M(1) to M(10) of the first storage stack ST1,
divides the calculated total value by 600 seconds which is the time
required to occupy the first storage stack ST1, and specifies the
quotient as a shorter-period vehicle stop time rate RS. In the
first storage stack ST1, the stack elements M(n) are updated one by
one at every 60 seconds which is the first cycle G1, so that the
shorter-period vehicle stop time rate RS is calculated at every
update. In other words, the process of step S810 uses the storage
of the first storage stack ST1 to determine the rate of the vehicle
stop time in the last 600 seconds as the shorter-period vehicle
stop time rate RS. The rate of the vehicle stop time denotes the
rate of the vehicle stop time to the total time (600 seconds in
this case).
[0098] The CPU also repeatedly calculates a longer-period vehicle
stop time rate RL at the second cycle G2 after elapse of 15 minutes
since the start of processing (step S820). Although the process of
step S820 is illustrated as if subsequent to step S810, this is for
convenience of illustration. Actually, like the process of step
S810 described above, the process of step S820 is performed
immediately after start of the vehicle stop time rate calculation
routine. In other words, the process of step S810 and the process
of step S820 are performed in parallel by time sharing.
[0099] At step S820, more specifically, the CPU calculates the
total value of the respective values stored in the stack elements
N(1) to N(10) of the second storage stack ST2, divides the
calculated total value by 900 seconds which is the time required to
occupy the second storage stack ST2, and specifies the quotient as
a longer-period vehicle stop time rate RL. In the second storage
stack ST2, the stack elements N(n) are updated one by one at every
90 seconds which is the second cycle G2, so that the longer-period
vehicle stop time rate RL is calculated at every update. In other
words, the process of step S820 uses the storage of the second
storage stack ST2 to determine the rate of the vehicle stop time in
the last 900 seconds as the longer-period vehicle stop time rate
RL. The rate of the vehicle stop time denotes the rate of the
vehicle stop time to the total time (900 seconds in this case). The
time required to occupy the second storage stack ST2, i.e., 900
seconds, corresponds to the start restriction time TL at step S650
described above.
[0100] The shorter-period vehicle stop time rate RS corresponds to
the "first vehicle stop time rate" described in [Technical
Problem]. The longer-period vehicle stop time rate RL corresponds
to the "second vehicle stop time rate" described in [Technical
Problem]. The ECU 50 and the vehicle stop time obtaining routine
and the vehicle stop time rate calculation routine performed by the
CPU of the ECU 50 correspond to the "first vehicle stop time rate
calculator" and the "second vehicle stop time rate calculator"
described in [Technical Problem].
[0101] As described above, the shorter-period vehicle stop time
rate RS is calculated after elapse of 10 minutes since the start of
processing, and the longer-period vehicle stop time rate RL is
calculated after elapse of 15 minutes since the start of
processing. This configuration provides a period of suspension
before determination of the respective first values respectively
using the first storage stack ST1 and the second storage stack ST2.
This period of suspension may be set to a predetermined initial
value needed by the system.
[0102] FIG. 14 is a flowchart showing the urban area/suburban area
determination routine performed at step S660 (FIG. 7). This urban
area/suburban area determination routine determines whether the
driving environment is an urban area or a suburban area, based on
the latest shorter-period vehicle stop time rate RS and the latest
longer-period vehicle stop time rate RL calculated in the vehicle
stop time rate calculation routine. Accordingly, the ECU 50 and the
urban area/suburban area determination routine performed by the CPU
of the ECU 50 correspond to the "driving environment predictor"
described in [Technical Problem].
[0103] As illustrated, when the process flow starts, the CPU
determines whether at least one of conditions is satisfied, i.e.,
the shorter-period vehicle stop time rate RS is equal to or higher
than a first reference value R1 and the longer-period vehicle stop
time rate RL is equal to or higher than a second reference value R2
(step S910). There is a relationship of R1>R2 between the first
reference value R1 and the second reference value R2. For example,
R1 is 48% and R2 is 44%. Upon determination that at least one of
the conditions is satisfied at step S910, the driving environment
is specified as an urban area (step S920). More specifically, a
value 1 is set to the urban area/suburban area classification P1.
After execution of step S920, the CPU goes to "Return" and
terminates this routine.
[0104] Upon determination that neither of the above two conditions
is satisfied at step S910, on the other hand, the CPU subsequently
determines whether both conditions are satisfied, i.e., the
shorter-period vehicle stop time rate RS is less than a third
reference value R3 and the longer-period vehicle stop time rate RL
is less than a fourth reference value R4 (step S930). There is a
relationship of R1>R3 between the third reference value R3 and
the above first reference value R1. There is also a relationship of
R2>R4 between the fourth reference value R4 and the above second
reference value R2. For example, R3 is 42% and R4 is 40%.
Furthermore, there is a relationship of R3>R4 between the third
reference value R3 and the fourth reference value R4. In other
words, there is a relationship of R1>R2>R3>R4 according to
the embodiment.
[0105] Upon determination that both the conditions are satisfied at
step S930, the driving environment is specified as a suburban area
(step S940). More specifically, a value 0 is set to the urban
area/suburban area classification P1. After execution of step S940,
the CPU goes to "Return" and terminates this routine. In the case
of negative answer at step S930, i.e., upon determination that at
least one of the conditions is not satisfied, the CPU immediately
goes to "Return" and terminates this routine. In other words, in
the case of negative answer at step S930, the CPU keeps unchanged
the value of the urban area/suburban area classification P1 set in
the previous cycle and terminates this routine.
[0106] The algorithm according to the urban area/suburban area
determination routine configured as described above determines
whether the driving environment is an urban area or a suburban
area, based on the shorter-period vehicle stop time rate RS and the
longer-period vehicle stop time rate RL. The following described
the reason of configuration of this algorithm.
[0107] FIG. 15 is a graph showing frequency distributions of the
shorter-period vehicle stop time rate RS in the urban area and in
the suburban area. FIG. 16 is a graph showing frequency
distributions of the longer-period vehicle stop time rate RL in the
urban area and in the suburban area. These graphs are created by
actually driving automobiles in urban areas and in suburban areas
and calculating the shorter-period vehicle stop time rate RS and
the longer-period vehicle stop time rate RL. As shown in FIG. 15,
in the distribution of the shorter-period vehicle stop time rate
RS, both suburban areas and urban areas are included in the range
of 35 to 53%. In the distribution of the longer-period vehicle stop
time rate RL, on the other hand, suburban areas are separated from
urban areas at about 42% as the boundary. According to these
results, the determination based on the shorter-period vehicle stop
time rate RS requires the shorter period of 10 minutes and has the
better responsiveness but the lower accuracy. The determination
based on the longer-period vehicle stop time rate RL, on the other
hand, requires the longer period of 15 minutes and has the worse
responsiveness but the higher accuracy.
[0108] The urban area/suburban area determination routine described
above uses a relatively high value of 48% in the above mixed range
(35 to 53%) as the reference value of the shorter-period vehicle
stop time rate RS at step S910 and is thus capable of specifying an
approach into an urban area with high responsiveness. The urban
area/suburban area determination routine, on the other hand, uses a
value of 40% that is slightly lower than 42%, at which urban areas
are clearly separated from suburban areas, as the reference value
of the longer-period vehicle stop time rate RL at step S930 and is
thus capable of specifying an approach into a suburban area with
high accuracy. The determination with regard to the longer-period
vehicle stop time rate RL at step S910 and the determination with
regard to the shorter-period vehicle stop time rate RS at step S930
are added, with a view to enhancing the accuracy of
determination.
[0109] Additionally, in the urban area/suburban area determination
routine described above, as shown in FIG. 17, the reference value
(R1, R2) for specifying a change from a suburban area to an urban
area is not identical with the reference value (R3, R2) for
specifying a change from an urban area to a suburban area, but
there is a certain difference between them. This prevents hunting
of the result of determination.
E. Advantageous Effects of Embodiment
[0110] The automobile 200 configured as described above determines
whether the current driving environment is an urban area or a
suburban area, based on the shorter-period vehicle stop time rate
RS calculated in the shorter period of 10 minutes and the
longer-period vehicle stop time rate RL calculated in the longer
period of 15 minutes and predicts the future driving environment on
the assumption that the result of determination is applied to the
future driving area. This prediction achieves both the
responsiveness and the accuracy as described previously.
Additionally, this does not need any complicated configuration like
an automotive navigation system but needs only the simple device
configuration.
[0111] The embodiment is configured not to perform calculation of
the vehicle stop time rate in the period from the key-on start-up
time to the time when the vehicle speed reaches the specified speed
V0. The calculated vehicle stop time rates are thus effectively
used in the system of idle reduction control. The idle reduction
control does not allow for idle reduction in the initial stage of a
vehicle start-up because of reasons like catalyst-warm-up.
Exclusion of the above period from calculation of the vehicle stop
time rate ensures the adequate control.
[0112] According to the embodiment, as shown in FIG. 6, the engine
10 is not restarted in the state that the SOC decreases to the
lower limit in the stop and start period t2-t3. An engine restart
due to shortage of SOC in the middle of the stop and start period
requires three times to even five times the amount of fuel required
in the case of an increase in power during operation of the engine
to increase the SOC. In other words, the fuel consumption effect
per unit SOC (for example, 1% SOC) during engine operation is three
times to five times better than that in the case of an engine
restart due to shortage of SOC in the middle of the stop and start
period. The automobile 200 of the embodiment accordingly has the
advantageous effect of improving the fuel consumption, compared
with the prior art.
[0113] Additionally, this embodiment determines the SOC
distribution request level P3 based on the urban area/suburban area
classification P1 (FIG. 4), which is set to achieve both the
responsiveness and the accuracy according to the urban
area/suburban area determination routine, and determines the
capacity for idle reduction based on the SOC distribution request
level P3 (FIG. 5). This enables the capacity for idle reduction to
be adequately determined in the available SOC range W of the
battery 40.
[0114] More specifically, the embodiment specifies the driving
environment as an urban area, when the shorter-period vehicle stop
time rate RS is equal to or higher than the first reference value
R1 (condition 1). In the case of an urban area (i.e., when the
urban area/suburban area classification P1="1"), the SOC
distribution request level P3 increases, and the capacity for idle
reduction is set to a greater value than the capacity set when the
condition 1 is not satisfied (in the case of a suburban area). The
embodiment also specifies the driving environment as an urban area,
when the longer-period vehicle stop time rate RL is equal to or
higher than the second reference value R2 (condition 2). In the
case of an urban area, the SOC distribution request level P3
increases, and the capacity for idle reduction is set to a greater
value than the capacity set when the condition 2 is not satisfied
(in the case of a suburban area). These result in more adequately
determining the capacity for idle reduction.
[0115] Additionally, the embodiment specifies the driving
environment as a suburban area, when the shorter-period vehicle
stop time rate RS is less than the third reference value R3 and
when the longer-period vehicle stop time rate RL is less than the
fourth reference value R4 (condition 3). In the case of a suburban
area, the SOC distribution request level P3 decreases, and the
capacity for idle reduction is set to a smaller value than the
capacity set when the condition 3 is not satisfied (in the case of
an urban area). In other words, when the shorter-period vehicle
stop time rate RS is less than the third reference value R3 and
when the longer-period vehicle stop time rate RL is less than the
fourth reference value R4, the capacity for charge control is set
to a greater value than the capacity set when this condition is not
satisfied. These result in more adequately determining the capacity
for charge control and thereby adequately determining the capacity
for idle reduction.
[0116] The embodiment accordingly enables the capacity for idle
reduction to be adequately determined and thus effectively prevents
the engine 10 from being restarted in the state that the SOC
reaches the lower limit in the stop and start period t2-t3. The
automobile 200 of the embodiment thus further improves the fuel
consumption.
F. Modifications
[0117] The present invention is not limited to the embodiment or
aspects described above but may be implemented by various other
aspects within the scope of the invention. Some examples of
possible modifications are given below.
[0118] Modification 1
[0119] The above embodiment is configured to determine the SOC
distribution request level P3 based on the urban area/suburban area
classification P1 and the vehicle state P2 and calculate the target
SOC based on the SOC distribution request level P3. Alternatively,
the configuration may be modified to directly calculate the target
SOC, based on the urban area/suburban area classification P1 and
the vehicle state P2. More specifically, the configuration may be
modified to directly calculate a distribution ratio of the
available SOC range of the battery to the capacity for charge
control and the capacity for idle reduction, based on the urban
area/suburban area classification P1 and the vehicle state P2.
[0120] Modification 2
[0121] The above embodiment calculates the SOC distribution request
level based on both the urban area/suburban area classification P1
and the vehicle state P. Alternatively, the configuration may be
modified to calculate the SOC distribution request level based on
only the urban area/suburban area classification P1.
[0122] Modification 3
[0123] The above embodiment and modifications 1 and 2 determine
whether the driving environment of the vehicle is an urban area or
a suburban area. The invention is, however, not limited to this
configuration. The configuration may be modified to determine an
index, which may take three or more values as the degree of
urbanization, instead of the two values of urban area and suburban
area. In this modification, the shorter-period vehicle stop time
rate RS and the longer-period vehicle stop time rate RL should
respectively be compared with two or more reference values.
[0124] Modification 4
[0125] In the above embodiment, the first to the fourth reference
values R1 to R4 are respectively set to 48%, 44%, 42% and 40%.
These values are only illustrative and may be changed to other
values according to the invention. The respective reference values
R1 to R4 are not necessarily fixed values but may be varied
according to the remaining amount of fuel and the remaining charge
of the battery.
[0126] Modification 5
[0127] The above embodiment and modifications 1 to 4 predict the
driving environment by comparing the shorter-period vehicle stop
time rate RS and the longer-period vehicle stop time rate RL with
the reference values. The invention is, however, not limited to
this configuration. For example, the driving environment may be
predicted, based on a change in shorter-period vehicle stop time
rate RS and a change in longer-period vehicle stop time rate RL. In
general, any configuration may be employed to predict the driving
environment based on the shorter-period vehicle stop time rate RS
and the longer-period vehicle stop time rate RL.
[0128] Modification 6
[0129] The above embodiment and modifications 1 to 5 determine the
classification between urban area and suburban area or the degree
of urbanization as the driving environment of the vehicle. The
invention is, however, not limited to this configuration. The
driving environment of the vehicle may be the degree of traffic
congestion or may be any parameter including a factor that causes a
stop of the vehicle (vehicle stop).
[0130] Modification 7
[0131] The above embodiment and modifications 1 to 6 are configured
to predict the driving environment of the vehicle. The vehicle
control device of the invention is not necessarily configured to
predict the driving environment. For example, the configuration may
be modified to directly set the capacity for idle reduction, based
on the shorter-period vehicle stop time rate RS and the
longer-period vehicle stop time rate RL.
[0132] Modification 8
[0133] The above embodiment specifies the driving environment as an
urban area when at least one of the following conditions is
satisfied, i.e., the shorter-period vehicle stop time rate RS is
equal to or higher than R1 and the longer-period vehicle stop time
rate RL is equal to or higher than R2 according to the urban
area/suburban area determination routine (FIG. 14). The invention
is, however, not limited to this configuration. The configuration
may be modified to specify the driving environment as an urban area
only when it is determined that RS is equal to or higher than R1.
In this modification, the longer-period vehicle stop time rate RL
may be used to specify whether the driving environment is a
suburban area. More specifically, for example, the configuration
may be modified to change the determination of step S910 in FIG. 14
to the determination of RS R1 and change the determination of step
S930 to the determination of RL<R4. This modification enables
the driving environment to be predicted with achieving both the
responsiveness and the accuracy by the simple configuration.
[0134] Modification 9
[0135] The above embodiment predicts the driving environment, based
on the shorter-period vehicle stop time rate RS and the
longer-period vehicle stop time rate RL. Alternatively, the
configuration of the invention may be modified to predict the
driving environment, based on one vehicle stop time rate, i.e., a
rate of vehicle stop time in a predetermined period.
[0136] Modification 10
[0137] In the above embodiment, the battery is a lead acid battery.
The invention is, however, not limited to this type of battery but
may be applied to any of various other types of batteries, such as
lithium ion battery and rocking chair-type battery. In the above
embodiment, the vehicle is an automobile. Alternatively the
invention may be applied to a vehicle other than automobile, such
as train.
[0138] Modification 11
[0139] Part of the functions configured by the software in the
above embodiment may be configured by hardware (for example,
integrated circuit), or part of the functions configured by the
hardware may be configured by software.
*Modification 12
[0140] Among components in the embodiment and the respective
modifications described above, components other than those
described in independent claims are additional components and may
be omitted as appropriate. For example, a modification may omit
charge control which suppresses the battery from being charged
during normal running to save the amount of fuel consumption and
charges the battery by regenerative power generation during
deceleration running.
REFERENCE SIGNS LIST
[0141] 10 Engine [0142] 15 Automatic transmission [0143] 20
Differential gear [0144] 25 Drive wheels [0145] 30 Starter [0146]
34 Drive mechanism [0147] 35 Alternator [0148] 40 Battery [0149] 50
ECU [0150] 70 Auxiliary machinery [0151] 72 Headlights [0152] 74
Air conditioner [0153] 82 Wheel speed sensor [0154] 84 Brake pedal
sensor [0155] 86 Accelerator opening sensor [0156] 88 Battery
current sensor [0157] 89 Alternator current sensor [0158] 90 Idle
reduction controller [0159] 100 SOC controller [0160] 110 Target
SOC estimator [0161] 112 Driving environment predictor [0162] 114
Vehicle state predictor [0163] 116 SOC distribution request level
calculator [0164] 118 Target SOC calculator [0165] 120 Battery SOC
calculator [0166] 130 Feedback controller [0167] 200 Automobile
* * * * *